1. Field of the Invention
The present invention relates to a method and system for sample preparation and, more particularly, to a method and system for preparing thin-film samples for transmission electron microscopy and sections of samples to be observed by scanning electron microscopy by making use of a focused ion beam (FIB) instrument and a scanning electron microscope (SEM).
2. Description of Related Art
One conventional method of preparing samples is disclosed, for example, in Japanese Patent No. 2,774,884 (paragraphs 0010 to 0018; FIGS. 1-6). In this method, the surface of the base plate of a sample is machined by a focused ion beam (FIB) from at least two angles to the surface of the base plate to isolate a tiny portion of the sample. At this time, the tip of a probe is connected with the isolated tiny sample portion. The sample portion can be conveyed into any arbitrary position by moving the probe.
Another conventional system is disclosed, for example, in JP-A-2003-7246 (paragraphs 0011 to 0030; FIGS. 3 and 4), and uses a transmission electron microscope equipped with two preliminary chambers. Each chamber has a focused ion beam instrument. When the first preliminary chamber is used for sample preparation, a sample from the second preliminary chamber is observed. When the second preliminary chamber is used for sample preparation, a sample from the first preliminary chamber is observed.
A further conventional charged-particle beam system is disclosed, for example, in JP-A-2005-322419 (paragraphs 0015 to 0017; FIG. 2) and uses a common moving device on which both a sample supply portion and a probe are carried when the sample is bonded to the probe.
(Sample Preparation for TEM)
In the technique of the above-cited Japanese Patent No. 2,774,884, sample preparation using a focused ion beam (FIB) instrument and moving of the prepared sample are carried out within one apparatus. This produces the problem that the time efficiency is low. Alternatively, a sample prepared by an FIB instrument has been moved to an optical microscope equipped with a manipulator and conveyed. In this equipment, the magnification of the optical microscope is low. Furthermore, it is difficult to convey the sample by the manipulator (glass probe). Hence, the sample has been conveyed at a low rate of success.
(Observations of Cross Sections for SEM)
A cross section of a sample has been observed by forming a hole by the machining function of an FIB instrument to thereby expose the cross section and then the cross section has been observed by making use of the SEM stage-tilting mechanism. There is the problem that the cross section to be observed is made invisible and, thus, made unobservable by sample tilting unless the hole is increased in area.